From: Christian Brauner <brauner@kernel.org>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mateusz Guzik <mjguzik@gmail.com>, Jens Axboe <axboe@kernel.dk>,
Christoph Hellwig <hch@lst.de>, Aleksa Sarai <cyphar@cyphar.com>,
Al Viro <viro@zeniv.linux.org.uk>,
Seth Forshee <sforshee@kernel.org>,
linux-fsdevel@vger.kernel.org, stable@vger.kernel.org
Subject: Re: [PATCH] file: always lock position
Date: Thu, 3 Aug 2023 20:02:03 +0200 [thread overview]
Message-ID: <20230803-libellen-klebrig-0a9e19dfa7dd@brauner> (raw)
In-Reply-To: <CAHk-=whQ51+rKrnUYeuw3EgJMv2RJrwd7UO9qCgOkUdJzcirWw@mail.gmail.com>
On Thu, Aug 03, 2023 at 08:45:54AM -0700, Linus Torvalds wrote:
> On Thu, 3 Aug 2023 at 02:53, Mateusz Guzik <mjguzik@gmail.com> wrote:
> >
> > So yes, atomics remain expensive on x86-64 even on a very moden uarch
> > and their impact is measurable in a syscall like read.
>
> Well, a patch like this should fix it.
>
> I intentionally didn't bother with the alpha osf version of readdir,
> because nobody cares, but I guess we could do this in the header too.
>
> Or we could have split the FMODE_ATOMIC_POS bit into two, and had a
> "ALWAYS" version and a regular version, but just having a
> "fdget_dir()" made it simpler.
>
> So this - together with just reverting commit 20ea1e7d13c1 ("file:
> always lock position for FMODE_ATOMIC_POS") - *should* fix any
> performance regression.
>
> But I have not tested it at all. So....
Yeah, this is my suggestion - and your earlier suggestion - in the
thread. Only thing that's missing is exclusion with seek on directories
as that's the heinous part.
next prev parent reply other threads:[~2023-08-03 18:05 UTC|newest]
Thread overview: 43+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-07-24 15:00 [PATCH] file: always lock position Christian Brauner
2023-07-24 15:53 ` Linus Torvalds
2023-07-24 16:19 ` Christian Brauner
2023-07-24 16:36 ` Linus Torvalds
2023-07-24 16:51 ` Linus Torvalds
2023-09-02 4:44 ` Al Viro
2023-07-24 17:23 ` Christian Brauner
2023-07-24 17:34 ` Linus Torvalds
2023-07-24 17:46 ` Christian Brauner
2023-07-24 18:01 ` Linus Torvalds
2023-07-24 18:05 ` Jens Axboe
2023-07-24 18:27 ` Linus Torvalds
2023-07-24 18:48 ` Christian Brauner
2023-07-24 22:25 ` Linus Torvalds
2023-07-24 22:56 ` Jens Axboe
2023-07-25 18:30 ` Linus Torvalds
2023-07-25 20:41 ` Jens Axboe
2023-07-25 20:51 ` Linus Torvalds
2023-07-25 20:58 ` Jens Axboe
2023-07-26 8:36 ` Christian Brauner
2023-07-26 10:31 ` David Laight
2023-07-26 12:53 ` Christian Brauner
2023-07-26 8:07 ` Christian Brauner
2023-07-24 16:46 ` Christian Brauner
2023-07-24 16:59 ` Linus Torvalds
2023-07-24 17:18 ` Linus Torvalds
2023-08-03 9:53 ` Mateusz Guzik
2023-08-03 14:15 ` Christian Brauner
2023-08-03 15:17 ` Mateusz Guzik
2023-08-03 15:18 ` Mateusz Guzik
2023-08-03 15:45 ` Linus Torvalds
2023-08-03 17:54 ` Mateusz Guzik
2023-08-03 18:02 ` Christian Brauner [this message]
2023-08-03 18:35 ` Linus Torvalds
2023-08-04 13:43 ` Christian Brauner
2023-08-04 13:59 ` Christoph Hellwig
2023-09-02 3:43 ` Al Viro
[not found] <20230804-turnverein-helfer-ef07a4d7bbec@brauner>
2023-08-05 11:46 ` Christian Brauner
2023-08-05 18:47 ` Linus Torvalds
2023-08-05 19:46 ` Linus Torvalds
2023-08-06 6:10 ` Christian Brauner
2023-08-06 13:25 ` Christian Brauner
2023-08-06 17:48 ` Linus Torvalds
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